Conventionally, in a holder unit of a hemming apparatus, a working tool holder holding a working tool is movably supported on a base so that the working tool can be disposed at a nonworking position and a working position. And, the movement of the working tool holder to the nonworking position of the working tool after working is normally effected by the resiliency of a resilient body such as a coil spring.
In this type of hemming apparatus, initial adjustment is performed on the mutual position between the working tool on the one hand, and a lower die and an upper die on the other hand. Since this initial adjustment is extremely difficult if the resiliency of the resilient body is being applied to the working tool holder, the initial adjustment is performed after temporarily demounting the resilient body from the holder unit. The resilient body is mounted again on the holder unit upon completion of the initial adjustment.
Incidentally, the demounting and mounting operation of such a resilient body involves complicated and troublesome operations including such as the disassembly and reassembly of the holder unit, as well as the removal of the working tool holder from the base and the reinstallation thereof on the base. Furthermore, in some type of holder unit, the operation of unloading and reloading the resilient body having powerful resiliency, particularly the coil spring, is required, with the result that the demounting and mounting operation of the resilient body becomes extremely dangerous.
The above-described problems are not limited to the initial adjustment and similarly occur in the case of readjustment as well.
The present invention has been devised in view of the above-described aspects, and its object is to provide a holder unit which, by making the resiliency of the resilient body small without demounting the resilient body, makes it possible to easily effect the initial adjustment and readjustment of the mutual position between the working tool on the one hand, and the lower die and the upper die on the other hand, and which makes it possible to demount and remount the resilient body easily and safely and to easily perform the assembly and reassembly thereof, as well as a hemming apparatus having this holder unit.